title: Temporal distribution of blood donations in three Brazilian blood centers and its repercussion on the blood supply.
abstract: BACKGROUND
  Seasonal distribution of blood donation hinders efforts to provide a safe and adequate blood supply leading to chronic and persistent shortages. This study examined whether holidays, geographical area and donation type (community versus replacement) has any impact on the fluctuation of donations.
  
  
  METHODS
  The numbers of blood donations from 2007 through 2010 in three Brazilian Retrovirus Epidemiological Donor Study II (REDS-II) participating centers were analyzed according to the week of donation. The weeks were classified as holiday or non-holiday. To compare donations performed during holiday versus non-holiday weeks, tabulations and descriptive statistics for weekly donations by blood center were examined and time series analysis was conducted.
  
  
  RESULTS
  The average weekly number of donations varied according to the blood center and type of week. The average number of donations decreased significantly during Carnival and Christmas and increased during the Brazilian National Donor Week. The fluctuation was more pronounced in Recife and Belo Horizonte when compared to São Paulo and higher among community donors.
  
  
  CONCLUSIONS
  National bank holidays affect the blood supply by reducing available blood donations. Blood banks should take into account these oscillations in order to plan local campaigns, aiming at maintaining the blood supply at acceptable levels.
authors.affiliation: Universidade Federal de São João del-Rei - UFSJ, São João del-Rei, MG, Brazil.
authors.forename: Claudia Di Lorenzo
authors.initials: CD
authors.lastname: Oliveira
authors.forename: Cesar
authors.initials: C
authors.lastname: de Almeida-Neto
authors.forename: Emily Jing
authors.initials: EJ
authors.lastname: Liu
authors.forename: Ester Cerdeira
authors.initials: EC
authors.lastname: Sabino
authors.forename: Silvana Carneiro
authors.initials: SC
authors.lastname: Leão
authors.forename: Paula
authors.initials: P
authors.lastname: Loureiro
authors.forename: David
authors.initials: D
authors.lastname: Wright
authors.forename: Brian
authors.initials: B
authors.lastname: Custer
authors.forename: Thelma Therezinha
authors.initials: TT
authors.lastname: Gonçalez
authors.forename: Ligia
authors.initials: L
authors.lastname: Capuani
authors.forename: Michael
authors.initials: M
authors.lastname: Busch
authors.forename: Anna Bárbara de Freitas Carneiro
authors.initials: AB
authors.lastname: Proietti
keywords: Blood banks; Blood donors; Brazil; Holidays; Temporal distribution; Time factors